Impulse group keying system



April 22, 1952 A. A. VARELA ,504

IMPULSE GROUP KEYING SYSTEM Filed Aug. 6, 1945 iP T= L SYNC. CONTROL ARTHUR A. VARELA Patented Apr. 22, 1952 UNITED STATES PATENT orrics IMPULSE GROUP KEYING SYSTEM Arthur A. Varela, Washington, D. C. ApplicationAugust 6, 1945, Serial No. 609,301

3 Claims. (Cl. 320-1) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to the operation of radar systems and is particularly directed to the problem of generating a controlled series of transmitted impulses. Such operation, in distinction to continuous impulse generation, affords comparative security from detection and direction finding operations.

It is accordingly an object of the invention to provide means for radiating a series of high frequency impulses. It is a more specific object of the invention to provide means for terminating operation of a high frequency impulse transmitter.

The invention will be further described with reference to the drawings, in which:

Fig. 1 shows a high frequency transmitter incorporating the invention, and

Fig. 2 shows another embodiment of the invention.

In Fig. l a high frequency transmitter is shown comprising split anode magnetron l and tank circuit 2 feeding antenna 3 by line 4 coupled to the tank through loop t. The transmitter is energized periodically by impulse voltages developed in secondary 6 of transformer 1 by a supply system fed from an alternating current source.

The power circuit may be connected across the primary of supply transformer H3, whose center tapped secondary H is connected in a full wave rectifying network having as filter components, condenser i i and choke 28, and charges artificial line 29 through relay Hi.

The charging of line 29 is controlled by relay operated magnetically from control key it. Relay E includes stationary electrode I? and magnetically responsive armature Is. As shown, the relay structure is enclosed in an evacuated envelope l9.

Key 55 operates to close an auxiliary circuit including source 2! and coil 22 which when energized brings armature i8 into contact with electrode H to connect artificial line 29 to the power supply and cause periodic operation of the transter under control of rotary gap 25, which is synchronized with the power supply frequency to eiiect discharge on each alternation thereof. In order to maintain proper timing relations, gap :25 is continuously running and due to the inertia of its mechanical drive system may not be keyed in parallel with transmitter power supply.

The charging circuit includes, in series, Winding 26 on relay is which also establishes a field controlling armature i8 and operates to maintain relay contact closed during the charging period of line The artificial line draws a charging current on each half cycle of the rectifier network and is discharged before the succeeding half cycle by gap 25.

Termination of the transmitted impulse group by opening of key 1 5% cannot result in an inchoate transmitted impulse since charging of line is once inaugurated, is maintained until completion. By the invention excessive arcing of t e relay contacts is also avoided, as these cannot be opened while passing a substantial current.

In the circuit of Fig. 2 relay i5 is positioned in the primary circuit of power transformer is which directly energizes artifical line 29 through chargchoke 28. Line 25 therefore is alternately harged positively and negati ely. Impulse disharge is obt ined by operation of vacuum tube 35, which may contain a small amount of gas. Upon conduction of tube 35 under application of a control voltage applied to grid 35 from su able synchronizing control device 37, the line dis charges through transformer l whose secondary 6 feeds an impulse transmitter as shown in Fig. 1. During such discharge the secondary of transformer i ii is blocked by charging choke 28.

It will be understood that the control pulse establishing conduction in switching tube 35 will be synchronized with the positive alternations charging line 29 by operation of the control device 37 energized by the alte hating power supply voltage.

As in Fig. 1, the operation of relay i5 is effective to maintain the charging current after opening of key I5 until the line current falls to an inconsequential value. Consequently iicomplete charging of line 29 will not occur to duce the generation of an inchoate transmitted impulse.

The invention described herein may manufactured and used by or for the GOVL1 "ent of the United states of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. An impulse group keying system for radio transmitters comprising condenser means for storing energy, means dischar ing the condenser means and feeding the stored energy to a transmitter, a power supply circuit for charging the condenser means, switch means in said circult, and control means for said switch energized in series with the charging circuit to maintain the switch closed while the condenser means is drawing substantial current.

2. An impulse group keying system for radio transmitters comprising condenser means for storing energy, constantly running switch means periodically operative to: connect the condenser means to a transmitter, circuit means for supplying current to the condenser means, a pair of nor mally open switch contacts in said circuit, contact control means forl closing said contacts at will, and other contactpontrol means for closing said contacts electrically operated and connected for energization by the charging current, by virtue of such connection the said other control means is rendered operative in dependency on the charging current to maintain the switch means closed while the condenser means is drawing substantial current.

3. An impulse group keying system for radio transmitters comprising condenser means for storing energy, constantly running switch means periodically operative toconnect the condenser means to a transmitter, a power supply circuit for charging the condenser means, normally open me- 4 chanical switching means in said circuit, and electromagnetic holding means for said mechanical switching means energized in series in said supply circuit.

ARTHUR A. VARELA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 755,032 Moore Mar. 22, 1904 1,217,516 Simpson Feb. 27, 1917 2,357,398 Gray Sept. 5, 1944 2,383,492 Klemperer Aug. 28, 1945 2,403,716 Goldberg et a1 July 9, 1946 2,415,116 Stiefel Feb. 4, 1947 2,459,858 Westcott Jan. 25, 1949 

